It is customary to have a cheese component in the topping of a pizza or similar Italian type pasta or sauced product. Such cheese component is usually applied to the pizza or other product after the tomato or other sauce has been cooked and is applied to the pastry shell or other product to be topped. The topped combination is then baked in an oven until the cheese is melted and achieves the now expected stringy consistency.
In attempting to prepare a shelf stable spreadable pizza topping sauce (a product which does not require refrigeration) containing cheese, it was determined that the cheeses and cheese food products usually used in fresh or frozen products would not retain their organoleptic properties when subjected to the high temperature processing necessary in the preparation of high-acid sauce combinations. It was desired to produce a sauce in which the cheese ingredient retained its particulate character and later achieved the meltdown and stringiness similar to mozzarella cheese when used as a topping on a variety of foods.
In using conventional cheeses, the following problems were encountered in these specific alternatives for the processing of the tomato sauce phase.
Retort processing, both agitated and static, proved unsatisfactory due to severe browning of the sauce and cheese phases. The cooked flavors imparted were unacceptable. Real mozzarella cheese was added to a tomato sauce, a low acid product which required retort processing. The cheese completely melted and lost its cheese character when the container was agitated during heating for the necessary time and temperature conditions to prepare the product. If such agitation was not present the sauce component in contact with the edges of the container would brown excessively. Usual tomato sauce products are somewhat less viscous than the desired product and tend to heat more uniformly without agitation. Examples of such products are Ragu and Progresso spaghetti sauces. Another product, Libby's Spred'n Heat Pizza flavored spread, is an homogeneous product resulting from use of cream cheese and retort processing. While giving adequate flavor response, there is no hint of particulate cheese in that product. Conventional cheese again proved unacceptable due to melting and blending.
Retort processing was also attempted using Nestle Fid-Bits.RTM. cheese analogue. These "cheese" bits were heat stable and did not melt in processing, but also failed to soften as the product was heated and in fact hardened when heating an english muffin topped with the cheese/tomato sauce product.
Aseptic processing was unacceptable due to the necessity of adding the cheese prior to passing the cheese containing tomato sauce through a heat exchanger and the resultant cheese melt during the high temperature and shear. It is to be noted that both the agitated retort process and the aseptic process have commercial limitations due to the necessity of specialized glass handling techniques.
When a synergistic preservation system, i.e., reduced pH, reduced water activity (A.sub.w), and pasteurization was used, there were resultant losses of tomato sauce identity and sensory limitations in the nature of the development of dry, pasty, salty or sweet flavors in the sauce due to high solute concentrations required for A.sub.w control. It was determined that stable products had unacceptable flavor characteristics and those sauces that had acceptable flavor were unstable and would support microbial growth.
In hot fill/low pH processing, the cheese demononstrated a sandy texture due to the low pH (near its isoelectric point) and developed sour off flavors. The cheese melted down during the processing operation. Sauces prepared using this method were essentially homogeneous mixtures with the melted cheese component incorporated in the tomato sauce.
Then an attempt was made to reduce the pH in natural mozzarella with the use of an acidulation process. This was accomplished by soaking the cheese in an acidified medium which resulted in an elevated moisture content, graininess and the lack of homogeniety of acid penetration. The resultant cheese lacked the melt stability required for subsequent pasteurization processing into the pizza sauce spread product.
It was thought that it would be possible to modify the natural cheese to become heat and acid stable and several stabilizer approaches were tried and found to be unacceptable. These approaches included a shortening, distilled monoglyceride (Myverol blend) and amioca starch stabilization system, a phosphate/citrate stabilizer and powdered milk and emulsified oil (Myverol blend) system, a locust bean gum and phosphate/citrate stabilization (disodium phosphate, sodium aluminum phosphate) system, a locust bean gum and citrate stabilization system, a locust bean gum and phosphate citrate stabilization and emulsified oil (Myverol blend) system, and a locust bean gum and phosphate/citrate stabilization and emulsification and wheat gluten (for bodying) system.
It is to be noted that locust bean gum/xanthan gum stabilizing systems are well known for use in heat reversible gels for salad and/or dessert uses. These uses in edible products are such that the pudding or aspic or other stabilized aqueous system will melt down in the mouth giving the impression of smooth or ultrasmooth consistency. Such uses permit the preparation of instant puddings, aspics and dietetic jellies, imitation sour cream, pie fillings and freeze-thaw resistant puddings.